The invention relates to an artificial hand and to a drive apparatus for such a hand, especially for the fingers of the hand, including a movable thumb and at least one further finger movable in a direction opposite the direction of a thumb movement.
Artificial hands and arm prosthesis with mechanically movable fingers are intended to enable the user thereof to perform the many gripping functions as they occur in day to day use, whereby the time required to perform each function should be minimized. Further, any artificial limb should approximate the appearance of a natural limb as much as possible.
In order to minimize the operational time of artificial limbs, it is necessary to provide drive means for the movable elements such as the finger and the thumb, which are adaptable in a wide range to the continuously varying requirements, especially with regard to the gripping force applied by the drive means to the fingers. Further, the drive means must be lockable in the gripping position of the fingers.
Efforts to meet the foregoing requirements have been made heretofore. Thus, pneumatic drive systems are known which receive their driving energy from high pressure bottles or air pressure conduits. Even gas pressure cartridges have been used as the energy supply for artificial limbs. German Patent Publication (DOS) No. 2,433,710 illustrates a device employing high pressure bottles which are rechargeable. However, all of these devices require an energy supply, the replenishing of which is time consuming for the invalid or user and the replenishing can take place only at specific locations. As a result, the range of use of prior art devices is substantially limited.
Other known drive mechanisms, for example, such as are described in German Patent Publication (DOS) No. 2,426,711, use an electric motor connected to the drive means for operating the fingers by means of rope and pulley arrangements. This type of drive requires additional locking mechanisms for arresting the fingers in the gripping position. A disadvantage common to the just described drive mechanisms with rope and pulleys as well as to drive mechanisms employing a pneumatic source of energy is seen in that these devices are of a relatively complicated structure and hence, are trouble prone, whereby the use value of these devices is substantially diminished.